Process of preparing films



' object 0 Patented Dec. 5, 1922.

UNITED STATES v 1,437,810 PATENT OFFICE.

NEIL S. KOCHER, OF ROCHESTER, NEW YORK, ASSIGNOR TO EASTMAN KODAK COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

PROCESS OF PREPARING FILMS.

No Drawing.

To all whom it may concern:

Be it known that I, NEIL S. KocHER, a citizen of the United States of America, residin at Rochester, in the county of Monroe and State of New York, have invented certain new and useful Improvements in Processes of Preparing Films, of which the following is a full, clear, and exact specification.

This invention relates to the preparation of films and particularly those containing cellulosic addition compounds, such as cellulose ethers or cellulose esters like nitrocellulose and aoetyl cellulose, in all of which compounds ether or ester groups have been added to the original cellulose molecules by reaction upon hydroxyl groups.

One object of my invention is to reduce the shrinkage of such films when subjected to the fluid treatment ordinarily employed in photographic manipulation. Another object is to reduce the shrinkage before the film base or support is coated with the photogra hic sensitive layer. Still another the invention is to reduce the shrinka e before the perforations are made in the lm. Other objects will hereinafter appear.

When film containing such cellulosic addition compounds of the types indicated above are successively immersed in the usual developing, fixing and washin baths and finally dried they noticeably s rink. This is ob ectionable when the film is used in certain processes of color photography which require accurate registration of images, and it is likewise objectionable in the case of ordinary motion picture work. When the perforations in the film for driving the latter throu h the projector are made before such fluid treatment, their relative positions become altered by the shrinkage, introducing difiiculties in their further use.

'While some of the shrinkage of a complete photographic film may be ascribed to the contraction of the gelatin layer containin the sensitive salts or image, it has been emonstrated that a very appreciable portion of the shrinkage is due tothe contraction of the support or base itself, containing the cellulosic addition com ounds. I have found that if such film ase or support be preshrunk, the subsequent difficu ties due to shrinkage by treatment in the Application filed December 23, 1921. Serial No. 524,534.

photographic baths will be greatlyv reduced and in some instances practically eliminated. While this preshrinking of the film, preferably before it is coated with the sensitive layer and before it is perforated, ma be performed on a support containing chiefly cellulose nitrate or celluloseacetate, I find that my invention is of especial value when the support contains cellulose ether. For this reason the following-description of an illustrative embodiment of my invention will be largely devoted to a cellulose ether form.

I have discovered that the preshrinkage condition can be created in film containing cellulose ether by immersing it in very cold Water until the tendency to shrinkage upon drying grows to the desired amount. Thus in the case of cellulose ether support, which is to be later coated with the sensitive photographic layer, I may immerse it in water ranging in temperature from 10 (1., down to the freezing point. I find that water at approximately 1 C., containing particles of ice mixed therein is very effective. The treatment may for example last from hour to 6 hours, the time being shorter the lower the temperature. The treatment may be carried out in any ordinary apparatus for fluid treating film. After the shrinkage tendency or condition is thus created, the shrinking takes place on drying.

The shrinking which takes place under these circumstances does not usually produce any troublesome buckling of the film. If the latter tends to occur, however, it can be prevented by holding the film flat during the shrinkage; as by holding it under tension.

This treatment of the cellulose ether film, particularl where the flexible base contains substantial y water-insoluble ethyl cellulose, is markedly different from that required when nitrocellulose and acetyl cellulose are the principal ingredients. The latter require warm water or warm weak alkaline solutions instead of cold one. For instance, the nitrate or acetate films may be immersed for several hours in warm solutions containing the same amount of sodium carbonate or caustic soda that is employed in the usual developing solutions, and then dried.

Hanng thus described my invention, what I claim as new and desire to secure by Letters Patent is 1. In the process of reducing the shrinkage in film containing cellulose ether, the step which comprises acting on said film with water near the freezing point to create a shrinkage tendency therein.

2. In the process of preshrinking film containing cellulose ether, the step of treating said film with water between 10 (1, and the freezing point until the shrinking condition is created.

3. The process of reparing film containing cellulose ether, w ich comprises the step of treating said film with water between 10 C., and the freezing point for 1% to 6 hours.

4. The process of preparing film containing water-insoluble cellulose ethers, which comprises the step of immersing said film in a bath of mixed water and ice until the shrinkage condition is created.

5. The process of preparing film containing cellulose, ether, which comprises the steps'of Shrinking said film by treatment with cold water and drying, the film being maintained against substantial buckling during said shrinking.

6. The process of preparing film contain ing flexible water-insoluble ethyl cellulose, which comprises the step of immersing said film in cold water until the shrinkage condition is created.

7. In the process of making photographic sensitive film having a support containing a cellulosic addition compound, the steps of shrinking said support and thereafter coating the latter with a photographicsensitive Layer.

8. In the process of making photographic sensitive film having a support containing a cellulosic addition compound, the ste s of shrinking the support while maintaining said support against substantial buckling and thereafter coating said support with a photographic sensitive la er.

9. In the process of ma ing photographic sensitive film having a support containing flexible water-insoluble ethyl cellulose, the steps of treating said support with water between 10. (1., and the freezing point for 1% to 6 hours, drying said support and then coating said support with a layer of light sensitive gelatino-silver-haloid emulsion.

10. In the process of making motion picture film having a support containing cellulose ether, the step of shrinking "said film and thereafter perforating the same.

11. In the recess of making motion picture film having a support containing cellulosic addition compound, the steps of shrinking the support, coating said support With a photographic sensitive layer, and then perforating the same.

12. In the process of making photographic sensitive film having a support containin cellulose ether, the steps of shrinking sai support and thereafter coating said support with a photographic sensitive layer.

13. As an article of manufacture, a strong, flexible, transparent, preshrunk support for photographic film comprised chiefly of cellulosic addition compounds.

14. As an article of manufacture, a strong, flexible, transparent, preshrunk su port for photographic film comprising cellu ose ether.

Signed at Rochester, New York, this 15th day of December 1921.

NEIL S. KOCHER.

Certificate o f Correctioh. I It is hereby certified iijI-Jetters Patent No. 1,437,810, granted December 5, 1922, upon the epplicetion of Neil S. Kocher, of Rochester, New York, for an improvement Processes of 'Prepariirg Films, errors appear in the printed specification requiring correction as follows: Page 1, line 69, for the word preshrinkage rea l and line 102, for the word one read ones; page 2, lines 14 and cleims 3 and 9, for the figure 1% read. i; and that the said Letters Patent should be read with eorrection therein that th same may conform to the record of "the case thePefent Ofl'lce.

Signed and sealed this 9th day of Janusr y, A. D., 19%.

. 1 I KARL FENNING,

" Acting Gmnmiam'mr ofPatents. 

